Purging as Damage Control

Ideological lockdown is a symptom of a movement in decline.
Witness:
Jeff Jarvis mentions in passing that he is a Democrat, and out came the witch-hunters saying he isn’t actually a liberal at all.
Oliver Willis says in the comments

Seriously, stop presenting yourself as a “liberal” by any stretch of the imagination Jeff.

Jeff answers him further down.

Who the hell made you the holder of the definition of liberal?
And how dare you put yourself above to decree who and who isn’t liberal? That’s really quite haughty. Very unliberal, I’d say.
Want to hear what I say about health insurance… abortion… gun control… welfare… and, most importantly, human rights (even the rights of Iraqis).
Hell, I’ll bet on many scales I’m more liberal than Howard Dean.
You don’t know what you’re talking about because what you’re talking about is me. So don’t presume to label me, mister. I find that insulting and offensive.

Jeff’s detractors are annoyed that he isn’t a party-line team player. But you know, folks, politics isn’t a game of football, nor is it war. It is okay if you think the other side is right once in a while (most people do, after all), and it’s also okay for a writer, any writer, to focus on whichever topics he or she chooses. Just because Jeff would rather write about new media and foreign policy instead of conventional liberal domestic issues doesn’t mean he doesn’t hold liberal views on those questions he puts in second or third place.
Regular readers of this site know that I can relate to Jeff’s experience and frustration. And the end result of all this has been for me to finally agree and say to heck with it, I’m not one of you after all. I’m an Independent now. And despite the fact that I still hold several liberal opinions, I no longer feel any sense of loyalty or affection for the Democratic Party.
Purging non-conformists might make you feel good, but it doesn’t help your side an iota.
I can’t help but think the intended audience for public heretic-banishing isn’t the target him or herself. It’s the heretic-banisher’s comrades. People on the losing side of political arguments know their support is bleeding away, so dissidents are furiously denounced as an object lesson for anyone else who might waver. It’s a form of damage control, which is why they don’t care if the tactic doesn’t make them any new friends.
UPDATE: Jeff Jarvis has more here, and he’s not very happy about it.
UPDATE: Armed Liberal jumps in, too. He asks the heretic-banishers to read George Orwell’s Homage to Catalonia, one of the best books ever written about the left by a leftist. What does Orwell’s book have to do with this political scrap? (Hint: It’s about left-wing anti-fascists, the Spanish Civil War, and the purge of dissident leftists by Josef Stalin.)
UPDATE: Photodude (who takes and posts better pictures than I probably ever will) joins the fray as well. He once invited me to join his Fence Party, and I accepted because the people in the middle make the most sense to me. At least for now.
UPDATE: Jeff at Caerdroia also prefers the middle. Unlike me, he was driven to the center by the excesses of the right.